You'll see in the slide deck that I also provide some tutorials around DANE and DNSSEC along the way.

Coincidentally, I learned on Facebook over the weekend that my friend Olle Johansson was speaking on this exact topic at the FOSDEM 2016 conference in Brussels this weekend. His slides about SIP & TLS are also available on SlideShare, and he has more recent information - and also the conclusion that we need to use "SIP Outbound" for any of this to work:

Olle's last slide about what we need to do hits on the key points - and I agree with his conclusions.

Let's look at how we can get more TLS used within SIP to bring about a more secure and trusted VoIP infrastructure!